V8 SpiderMonkey JavaScriptCore Chakra Carakan KJS Other
⬤ Minor difference (1 point) ⬤ Small feature (2 points) ⬤ Medium feature (4 points) ⬤ Large feature (8 points)
Compilers/polyfills Desktop browsers Servers/runtimes Mobile
Feature name Current browser ES6
Trans-
piler		 Traceur Babel +
core-js[2]		 Closure JSX Type-
Script +
core-js		 es6-shim KQ
4.14[3]		 IE 7 IE 8 IE 9 IE 10 IE 11 Edge 12[4] Edge 13[4] Edge 14[4] Edge 15[4] FF 38
ESR		 FF 44 FF 45 ESR FF 46 FF 47 FF 48 FF 49 FF 50 FF 51 FF 52 FF 53 Beta FF 54 Aurora FF 55 Nightly OP 12 OP 12.10 CH 47,
OP 34[1]		 CH 48,
OP 35[1]		 CH 49,
OP 36[1]		 CH 50,
OP 37[1]		 CH 51,
OP 38[1]		 CH 52,
OP 39[1]		 CH 53,
OP 40[1]		 CH 54,
OP 41[1]		 CH 55,
OP 42[1]		 CH 56,
OP 43[1]		 CH 57,
OP 44[1]		 CH 58,
OP 45[1]		 CH 59,
OP 46[1]		 SF 5 SF
5.1		 SF 6 SF 6.1,
SF 7		 SF 7.1,
SF 8		 SF 9 SF 10 SF 10.1 SF TP WK Rhino 1.7 PJS Echo JS XS6 JXA Node 0.10[5] Node 0.12[5] io.js[5] Node 4[5] Node 5[5] Node 6.0-6.4[5] Node >=6.5 <7[5] Node 7.0-7.5[5] Node >=7.6 <8[5] AN 4.0 AN 4.1 AN 4.2 AN 4.3 AN 4.4 AN 5.0 AN 5.1 iOS 5.1 iOS 6 iOS 7 iOS 8 iOS 9 iOS 10 DUK 20
Optimisation
§proper tail calls (tail call optimisation) 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2
§direct recursion No Flag[6] No No No No[7] No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No Flag Flag Flag Flag Flag Flag Flag Flag Flag No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Flag Flag Flag No No No No No No No No No No No No Yes Yes
§mutual recursion No Flag[6] No No No No[7] No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No Flag Flag Flag Flag Flag Flag Flag Flag Flag No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Flag Flag Flag No No No No No No No No No No No No Yes Yes
Syntax
§default function parameters MDN (Mozilla Development Network) logo  4/7 4/7 4/7 4/7 0/7 5/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 3/7 4/7 4/7 4/7 4/7 4/7 4/7 4/7 6/7 6/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 0/7 0/7 4/7 7/7 0/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 7/7 0/7
§basic functionality Yes Yes Yes Yes No Yes No No No No No No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§explicit undefined defers to the default Yes Yes Yes Yes No Yes No No No No No No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§defaults can refer to previous params Yes Yes Yes Yes No Yes No No No No No No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§arguments object interaction Yes Yes Yes No No Yes No No No No No No No No Flag Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§temporal dead zone No No No No No Yes No No No No No No No Flag Flag Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§separate scope No No No Yes No No No No No No No No No Flag Flag Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§new Function() support No No No No No No[7] No No No No No No No Flag Flag Yes Yes No No No No No No No No No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No[0] Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§rest parameters MDN (Mozilla Development Network) logo  2/5 4/5 3/5 2/5 3/5 4/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 4/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 0/5 0/5 3/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 0/5
§basic functionality Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§function 'length' property Yes Yes Yes No Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§arguments object interaction No Yes Yes No No Yes No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§can't be used in setters No Yes No Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§new Function() support No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No[0] Yes No No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§spread (...) operator MDN (Mozilla Development Network) logo  8/15 15/15 13/15 12/15 2/15 4/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 12/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 0/15 0/15 5/15 9/15 15/15 15/15 15/15 15/15 0/15 0/15 10/15 15/15 11/15 0/15 0/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 5/15 9/15 15/15 0/15
§with arrays, in function calls Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with arrays, in array literals Yes Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with sparse arrays, in function calls Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with sparse arrays, in array literals No Yes No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with strings, in function calls No Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with strings, in array literals No Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with astral plane strings, in function calls No Yes Yes No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with astral plane strings, in array literals No Yes Yes No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with generator instances, in calls No Yes Yes Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generator instances, in arrays No Yes Yes Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generic iterables, in calls Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generic iterables, in arrays Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with instances of iterables, in calls Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with instances of iterables, in arrays Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§spreading non-iterables is a runtime error Yes Yes No Yes No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No Flag Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§object literal extensions MDN (Mozilla Development Network) logo  6/6 6/6 6/6 4/6 5/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 1/6 5/6 6/6 6/6 6/6 6/6 0/6 0/6 5/6 6/6 5/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 1/6 5/6 6/6 4/6
§computed properties Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes
§shorthand properties Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§shorthand methods Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§string-keyed shorthand methods Yes Yes Yes No Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§computed shorthand methods Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§computed accessors Yes Yes Yes No No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for..of loops MDN (Mozilla Development Network) logo  4/9 9/9 9/9 6/9 2/9 3/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 6/9 7/9 7/9 9/9 7/9 7/9 7/9 7/9 7/9 7/9 7/9 7/9 7/9 7/9 9/9 9/9 9/9 0/9 0/9 7/9 7/9 7/9 7/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 2/9 8/9 9/9 9/9 9/9 9/9 0/9 0/9 7/9 9/9 8/9 0/9 7/9 7/9 7/9 7/9 7/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 0/9 0/9 7/9 0/9 0/9 0/9 2/9 8/9 9/9 0/9
§with arrays Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§with sparse arrays Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§with strings No Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§with astral plane strings No Yes Yes No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§with generator instances No Yes Yes Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§with generic iterables Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§with instances of generic iterables Yes[8] Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§iterator closing, break No Yes Yes No No No No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§iterator closing, throw No Yes Yes No No No No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§octal and binary literals 2/4 2/4 4/4 4/4 0/4 4/4 2/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 2/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4
§octal literals Yes Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§binary literals Yes Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§octal supported by Number() No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§binary supported by Number() No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§template literals MDN (Mozilla Development Network) logo  3/5 4/5 4/5 3/5 4/5 3/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 4/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 4/5 5/5 5/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 0/5
§basic functionality Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§toString conversion No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§tagged template literals Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§passed array is frozen Yes Yes Yes No Yes No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§line break normalisation No Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§RegExp "y" and "u" flags MDN (Mozilla Development Network) logo  0/5 3/5 3/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 2/5 5/5 5/5 5/5 2/5 2/5 2/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 2/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 0/5 0/5 2/5 2/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 0/5
§"y" flag No No No No No No[7] No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"y" flag, lastIndex No No No No No No[7] No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"u" flag No Yes Yes No No No[7] No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"u" flag, Unicode code point escapes No Yes Yes No No No[7] No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"u" flag, case folding No Yes Yes No No No[7] No No No No No No No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§destructuring, declarations MDN (Mozilla Development Network) logo  14/22 20/22 21/22 19/22 12/22 15/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 21/22 22/22 19/22 19/22 19/22 19/22 21/22 21/22 21/22 21/22 21/22 21/22 22/22 22/22 22/22 0/22 0/22 0/22 0/22 21/22 21/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 0/22 0/22 0/22 0/22 9/22 19/22 22/22 22/22 22/22 22/22 0/22 0/22 12/22 21/22 19/22 0/22 0/22 0/22 0/22 0/22 21/22 22/22 22/22 22/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 9/22 19/22 22/22 0/22
§with arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with sparse arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with strings Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with astral plane strings No Yes Yes No No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with generator instances No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with instances of generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§iterator closing No Yes Yes No No No No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§trailing commas in iterable patterns Yes No Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with objects Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§object destructuring with primitives Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§trailing commas in object patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§throws on null and undefined Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§computed properties Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§multiples in a single var statement Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§nested Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§in for-in loop heads No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§in for-of loop heads Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§in catch heads No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§rest Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§defaults Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§defaults, let temporal dead zone No No Flag No No Yes No No No No No No No No Flag Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§destructuring, assignment MDN (Mozilla Development Network) logo  17/24 23/24 24/24 17/24 11/24 19/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 23/24 24/24 20/24 21/24 21/24 21/24 23/24 23/24 23/24 23/24 23/24 23/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 23/24 23/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 12/24 21/24 24/24 24/24 24/24 24/24 0/24 0/24 14/24 24/24 21/24 0/24 0/24 0/24 0/24 0/24 23/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 12/24 21/24 24/24 0/24
§with arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with sparse arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with strings Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with astral plane strings No Yes Yes No No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with generator instances No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with instances of generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§iterator closing No No Yes No No No No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§iterable destructuring expression Yes Yes Yes No No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§chained iterable destructuring Yes Yes Yes No No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§trailing commas in iterable patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with objects Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§object destructuring with primitives Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§trailing commas in object patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§object destructuring expression Yes Yes Yes No No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§parenthesised left-hand-side is a syntax error No Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§chained object destructuring Yes Yes Yes No No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§throws on null and undefined Yes Yes Yes No Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§computed properties Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§nested Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§rest Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§nested rest No Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§empty patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§defaults Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§destructuring, parameters MDN (Mozilla Development Network) logo  15/23 19/23 20/23 18/23 12/23 15/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 22/23 23/23 18/23 18/23 18/23 18/23 19/23 19/23 19/23 19/23 20/23 20/23 23/23 23/23 23/23 0/23 0/23 0/23 0/23 22/23 22/23 23/23 23/23 23/23 23/23 23/23 23/23 23/23 23/23 23/23 0/23 0/23 0/23 0/23 10/23 18/23 23/23 23/23 23/23 23/23 0/23 0/23 12/23 23/23 18/23 0/23 0/23 0/23 0/23 0/23 22/23 23/23 23/23 23/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 0/23 10/23 18/23 23/23 0/23
§with arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with sparse arrays Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with strings Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§with astral plane strings No Yes Yes No No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with generator instances No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§with generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with instances of generic iterables No Yes Yes Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§iterator closing No No Yes No No No No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§trailing commas in iterable patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§with objects Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§object destructuring with primitives Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§trailing commas in object patterns Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§throws on null and undefined Yes Yes Yes No Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§computed properties Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§nested Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§'arguments' interaction Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§new Function() support No No No No No No[7] No No No No No No No No Flag Yes Yes No No No No No No No No No No Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§in parameters, function 'length' property Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§rest Yes Yes Yes Yes Yes Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§empty patterns Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§defaults Yes Yes Yes Yes No Yes No No No No No No No No Flag Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§defaults, separate scope No No No Yes No No No No No No No No No No Flag Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§defaults, new Function() support No No No No No No[7] No No No No No No No No Flag Yes Yes No No No No No No No No No No Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No[0] Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Unicode code point escapes 1/2 1/2 1/2 1/2 0/2 1/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2
§in strings Yes Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§in identifiers No No No No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§new.target MDN (Mozilla Development Network) logo  0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 1/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 0/2
§in constructors No No No No No No No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§assignment is an early error No No No No No No No No No No No No No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
Bindings
§const MDN (Mozilla Development Network) logo  10/16 14/16 14/16 14/16 0/16 14/16 0/16 2/16 0/16 0/16 0/16 0/16 12/16 12/16 12/16 16/16 16/16 12/16 12/16 12/16 12/16 12/16 12/16 12/16 12/16 16/16 16/16 16/16 16/16 16/16 1/16 1/16 9/16 9/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 1/16 1/16 1/16 1/16 1/16 16/16 16/16 16/16 16/16 0/16 1/16 8/16 16/16 10/16 0/16 1/16 1/16 9/16 9/16 16/16 16/16 16/16 16/16 1/16 1/16 1/16 1/16 1/16 1/16 1/16 0/16 1/16 1/16 1/16 1/16 16/16 2/16
§basic support Yes Yes Yes Yes No Yes No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§is block-scoped Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§cannot be in statements Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§redefining a const is an error Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for loop statement scope Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for-in loop iteration scope No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for-of loop iteration scope No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§temporal dead zone No No Flag No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§basic support (strict mode) Yes Yes Yes Yes No Yes No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§is block-scoped (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§cannot be in statements (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§redefining a const (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for loop statement scope (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for-in loop iteration scope (strict mode) No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for-of loop iteration scope (strict mode) No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§temporal dead zone (strict mode) No No Flag No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§let MDN (Mozilla Development Network) logo  8/12 10/12 10/12 10/12 0/12 10/12 0/12 0/12 0/12 0/12 0/12 0/12 10/12 10/12 10/12 12/12 12/12 0/12 10/12 10/12 10/12 10/12 10/12 10/12 10/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 6/12 6/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12 0/12 12/12 12/12 12/12 12/12 0/12 0/12 8/12 12/12 0/12 0/12 0/12 0/12 6/12 6/12 12/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 0/12 12/12 0/12
§basic support Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§is block-scoped Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§cannot be in statements Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for loop statement scope Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§temporal dead zone No No Flag No No No No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for/for-in loop iteration scope No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§basic support (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§is block-scoped (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§cannot be in statements (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for loop statement scope (strict mode) Yes Yes Yes Yes No Yes No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§temporal dead zone (strict mode) No No Flag No No No No No No No No No Yes Yes Yes Yes Yes Flag[11] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§for/for-in loop iteration scope (strict mode) No Yes Yes Yes No Yes No No No No No No No No No Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§block-level function declaration[12] No Yes Yes Yes No No No No No No No No Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
Functions
§arrow functions MDN (Mozilla Development Network) logo  8/13 11/13 9/13 10/13 8/13 9/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 8/13 13/13 13/13 13/13 8/13 11/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 0/13 0/13 11/13 11/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 13/13 0/13 0/13 0/13 0/13 0/13 0/13 13/13 13/13 13/13 13/13 0/13 0/13 7/13 12/13 0/13 0/13 0/13 0/13 9/13 10/13 13/13 13/13 13/13 13/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 0/13 13/13 0/13
§0 parameters Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§1 parameter, no brackets Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§multiple parameters Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§lexical "this" binding Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"this" unchanged by call or apply Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§can't be bound, can be curried Yes Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§lexical "arguments" binding No Yes Yes Yes No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§no line break between params and => No Yes Yes Yes No Yes No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§correct precedence No Yes No Yes No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§no "prototype" property No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§lexical "super" binding in constructors Yes Yes No No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§lexical "super" binding in methods Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§lexical "new.target" binding No No No No No No No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§class MDN (Mozilla Development Network) logo  17/24 17/24 19/24 13/24 16/24 19/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 24/24 24/24 24/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 0/24 16/24 24/24 24/24 24/24 24/24 0/24 0/24 22/24 24/24 18/24 0/24 0/24 0/24 0/24 0/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 16/24 24/24 0/24
§class statement Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§is block-scoped No No Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§class expression Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§anonymous class Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§constructor Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§prototype methods Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§string-keyed methods Yes Yes Yes No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§computed prototype methods Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§optional semicolons Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§static methods Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§computed static methods Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§accessor properties Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§computed accessor properties Yes Yes Yes Yes No Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§static accessor properties Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§computed static accessor properties Yes Yes Yes No No Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§class name is lexically scoped Yes Yes Yes No No Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§computed names, temporal dead zone No No No No No Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§methods aren't enumerable No No Yes No Yes No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§implicit strict mode Yes Yes Yes No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§constructor requires new No No Yes No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§extends No[13] No[13] No[13] No[14] No[14] No[15] No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§extends expressions No[13] No[13] No[13] No No[14] No[15] No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§extends null Yes Yes No No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§new.target No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§super MDN (Mozilla Development Network) logo  7/8 7/8 4/8 5/8 7/8 7/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 8/8 8/8 8/8 0/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 0/8 6/8 8/8 8/8 8/8 8/8 0/8 0/8 6/8 8/8 7/8 0/8 0/8 0/8 0/8 0/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 6/8 8/8 0/8
§statement in constructors Yes Yes No Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§expression in constructors Yes Yes No Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§in methods, property access Yes Yes Yes No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§in methods, method calls Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§method calls use correct "this" binding Yes Yes Yes Yes Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§constructor calls use correct "new.target" binding No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§is statically bound Yes Yes Yes No Yes Yes No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§super() invokes the correct constructor Yes Yes No Yes Yes Yes No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§generators MDN (Mozilla Development Network) logo  0/27 24/27 24/27 16/27 0/27 0/27 0/27 0/27 0/27 0/27 0/27 0/27 0/27 0/27 27/27 27/27 27/27 20/27 21/27 25/27 25/27 25/27 25/27 25/27 25/27 25/27 25/27 27/27 27/27 27/27 0/27 0/27 20/27 20/27 23/27 27/27 27/27 27/27 27/27 27/27 27/27 27/27 27/27 27/27 27/27 0/27 0/27 0/27 0/27 0/27 0/27 27/27 27/27 27/27 27/27 0/27 0/27 16/27 27/27 0/27 0/27 0/27 0/27 20/27 20/27 27/27 27/27 27/27 27/27 0/27 0/27 0/27 0/27 0/27 0/27 16/27 0/27 0/27 0/27 0/27 0/27 27/27 0/27
§basic functionality No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§generator function expressions No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§correct "this" binding No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§can't use "this" with new No No No No No No No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§sending No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%GeneratorPrototype% No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%GeneratorPrototype% prototype chain No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%GeneratorPrototype%.constructor No No No No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%GeneratorPrototype%.throw No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%GeneratorPrototype%.return No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§yield operator precedence No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, arrays No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, sparse arrays No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, strings No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, astral plane strings No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, generator instances No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, generic iterables No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, instances of iterables No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield * on non-iterables is a runtime error No Yes No No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§yield *, iterator closing No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§yield *, iterator closing via throw() No Yes Yes[16] No No No No No No No No No No No Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§shorthand generator methods No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§string-keyed shorthand generator methods No Yes Yes[16] No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§computed shorthand generators No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§shorthand generator methods, classes No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§computed shorthand generators, classes No Yes Yes[16] Yes No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§shorthand generators can't be constructors No No Yes[16] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
Built-ins
§typed arrays MDN (Mozilla Development Network) logo  0/46 0/46 45/46 0/46 0/46 45/46 0/46 8/46 0/46 0/46 0/46 16/46 16/46 42/46 44/46 46/46 46/46 41/46 42/46 42/46 43/46 43/46 45/46 45/46 45/46 45/46 46/46 46/46 46/46 46/46 19/46 19/46 43/46 43/46 43/46 43/46 46/46 46/46 46/46 46/46 46/46 46/46 46/46 46/46 46/46 0/46 16/46 18/46 18/46 18/46 18/46 46/46 46/46 46/46 46/46 0/46 18/46 37/46 46/46 46/46 0/46 23/46 23/46 43/46 43/46 43/46 46/46 46/46 46/46 15/46 16/46 16/46 16/46 19/46 19/46 23/46 0/46 16/46 18/46 18/46 18/46 46/46 19/46
§Int8Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Uint8Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Uint8ClampedArray MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes
§Int16Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Uint16Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Int32Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Uint32Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Float32Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Float64Array MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Int8) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Uint8) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Int16) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Uint16) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Int32) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Uint32) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Float32) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§DataView (Float64) MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§ArrayBuffer[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§constructors require new No No Yes No No Yes[10] No No No No No No No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No No No No Yes Yes
§constructors accept generic iterables No No Yes No No Yes[10] No No No No No No No No No Yes Yes No No No No No No No No No Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§correct prototype chains No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.from MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.of MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.subarray MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes
§%TypedArray%.prototype.join MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.indexOf MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.lastIndexOf MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.slice MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.every MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.filter MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.forEach MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.map MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.reduce MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.reduceRight MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.reverse MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.some MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.sort MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.copyWithin MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.find MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.findIndex MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.fill MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§%TypedArray%.prototype.keys MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%TypedArray%.prototype.values MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%TypedArray%.prototype.entries MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%TypedArray%.prototype[Symbol.iterator] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes No
§%TypedArray%[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Map MDN (Mozilla Development Network) logo  0/19 14/19 19/19 14/19 0/19 19/19 15/19 0/19 0/19 0/19 0/19 0/19 8/19 16/19 18/19 18/19 19/19 15/19 17/19 18/19 18/19 18/19 18/19 18/19 18/19 18/19 18/19 19/19 19/19 19/19 0/19 0/19 17/19 17/19 17/19 17/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 0/19 0/19 0/19 0/19 11/19 18/19 19/19 19/19 19/19 19/19 0/19 0/19 17/19 19/19 18/19 0/19 13/19 13/19 17/19 17/19 17/19 19/19 19/19 19/19 0/19 0/19 0/19 0/19 0/19 0/19 16/19 0/19 0/19 0/19 11/19 18/19 19/19 0/19
§basic functionality No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§constructor arguments No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor requires new No No Yes No No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor accepts null No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§constructor invokes set No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§iterator closing No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Map.prototype.set returns this No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§-0 key converts to +0 No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Map.prototype.size MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.delete MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.clear MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.forEach MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.keys MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.values MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype.entries MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map.prototype[Symbol.iterator] MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Map.prototype isn't an instance No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Map iterator prototype chain No Yes Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Map[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Set MDN (Mozilla Development Network) logo  0/19 14/19 19/19 14/19 0/19 19/19 15/19 0/19 0/19 0/19 0/19 0/19 8/19 16/19 18/19 18/19 19/19 15/19 17/19 18/19 18/19 18/19 18/19 18/19 18/19 18/19 18/19 19/19 19/19 19/19 0/19 0/19 17/19 17/19 17/19 17/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 19/19 0/19 0/19 0/19 0/19 11/19 18/19 19/19 19/19 19/19 19/19 0/19 0/19 18/19 19/19 18/19 0/19 13/19 13/19 17/19 17/19 17/19 19/19 19/19 19/19 0/19 0/19 0/19 0/19 0/19 0/19 16/19 0/19 0/19 0/19 11/19 18/19 19/19 0/19
§basic functionality No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§constructor arguments No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor requires new No No Yes No No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor accepts null No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§constructor invokes add No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§iterator closing No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Set.prototype.add returns this No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§-0 key converts to +0 No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Set.prototype.size MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.delete MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.clear MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.forEach MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.keys MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.values MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype.entries MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set.prototype[Symbol.iterator] MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Set.prototype isn't an instance No Yes Yes Yes No Yes[10] Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Set iterator prototype chain No Yes Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Set[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§WeakMap MDN (Mozilla Development Network) logo  0/12 6/12 12/12 9/12 0/12 12/12 0/12 0/12 0/12 0/12 0/12 0/12 6/12 11/12 11/12 11/12 12/12 8/12 10/12 10/12 11/12 11/12 11/12 11/12 11/12 11/12 11/12 12/12 12/12 12/12 0/12 0/12 11/12 11/12 11/12 11/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 7/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 9/12 11/12 11/12 0/12 7/12 8/12 11/12 11/12 11/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12 6/12 9/12 0/12 0/12 0/12 7/12 12/12 12/12 0/12
§basic functionality No Yes Yes Yes No Yes[10] No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§constructor arguments No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor requires new No No Yes No No Yes[10] No No No No No No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§constructor accepts null No Yes Yes Yes No Yes[10] No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§constructor invokes set No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§frozen objects as keys No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§iterator closing No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§WeakMap.prototype.set returns this MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§WeakMap.prototype.delete MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§no WeakMap.prototype.clear method MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§.has, .get and .delete methods accept primitives No No Yes Yes No Yes[10] No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No ? ? ? No No Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§WeakMap.prototype isn't an instance No Yes Yes No No Yes[10] No No No No No No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§WeakSet MDN (Mozilla Development Network) logo  0/11 5/11 11/11 8/11 0/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 10/11 10/11 10/11 11/11 9/11 9/11 9/11 10/11 10/11 10/11 10/11 10/11 10/11 10/11 11/11 11/11 11/11 0/11 0/11 10/11 10/11 10/11 10/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 9/11 10/11 10/11 0/11 6/11 7/11 10/11 10/11 10/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 5/11 8/11 0/11 0/11 0/11 0/11 11/11 11/11 0/11
§basic functionality No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§constructor arguments No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§constructor requires new No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§constructor accepts null No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§constructor invokes add No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§iterator closing No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§WeakSet.prototype.add returns this No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§WeakSet.prototype.delete No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§no WeakSet.prototype.clear method No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§.has and .delete methods accept primitives No No Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No ? ? ? No No Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§WeakSet.prototype isn't an instance No Yes Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Proxy MDN (Mozilla Development Network) logo [17] 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 34/34 34/34 34/34 34/34 28/34 30/34 30/34 30/34 30/34 30/34 34/34 34/34 34/34 34/34 34/34 34/34 34/34 0/34 0/34 0/34 0/34 33/34 34/34 34/34 34/34 34/34 34/34 34/34 34/34 34/34 34/34 34/34 0/34 0/34 0/34 0/34 0/34 0/34 34/34 34/34 34/34 34/34 0/34 0/34 27/34 34/34 0/34 0/34 0/34 0/34 0/34 0/34 34/34 34/34 34/34 34/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 0/34 34/34 11/34
§constructor requires new No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§no "prototype" property No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"get" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"get" handler, instances of proxies No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"get" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"set" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"set" handler, instances of proxies No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"set" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"has" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"has" handler, instances of proxies No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"has" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"deleteProperty" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"deleteProperty" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"getOwnPropertyDescriptor" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"getOwnPropertyDescriptor" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"defineProperty" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"defineProperty" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"getPrototypeOf" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"getPrototypeOf" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"setPrototypeOf" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"setPrototypeOf" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"isExtensible" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"isExtensible" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"preventExtensions" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"preventExtensions" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"ownKeys" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§"ownKeys" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes No[0] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"apply" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"apply" handler invariant No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"construct" handler MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"construct" handler invariants No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Proxy.revocable MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.isArray support No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§JSON.stringify support No No No No No No[7] No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect MDN (Mozilla Development Network) logo [18] 0/20 0/20 14/20 14/20 0/20 18/20 14/20 0/20 0/20 0/20 0/20 0/20 0/20 13/20 20/20 20/20 20/20 0/20 17/20 20/20 19/20 19/20 19/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 0/20 0/20 0/20 0/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 20/20 0/20 0/20 0/20 0/20 0/20 0/20 20/20 20/20 20/20 20/20 0/20 0/20 14/20 16/20 0/20 0/20 0/20 0/20 0/20 0/20 20/20 20/20 20/20 20/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 0/20 20/20 14/20
§Reflect.get MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.set MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.has MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.deleteProperty MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.getOwnPropertyDescriptor MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.defineProperty MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.getPrototypeOf MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.setPrototypeOf MDN (Mozilla Development Network) logo  No No No[13] No[13] No No[13] No[13] No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.isExtensible MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.preventExtensions MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.ownKeys, string keys MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.ownKeys, symbol keys MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.apply MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.construct MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.construct sets new.target meta-property No No No No No No[7] No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect.construct creates instances from third argument No No Yes Yes No Yes[10] Yes No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect.construct, Array subclassing No No No No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect.construct, RegExp subclassing No No No No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes No No No Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect.construct, Function subclassing No No No No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Reflect.construct, Promise subclassing No No No No No Yes[10] No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Promise MDN (Mozilla Development Network) logo  0/8 4/8 8/8 7/8 0/8 8/8 7/8 0/8 0/8 0/8 0/8 0/8 0/8 7/8 8/8 8/8 8/8 6/8 6/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 7/8 7/8 7/8 7/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 4/8 6/8 8/8 8/8 8/8 8/8 0/8 0/8 4/8 8/8 0/8 0/8 4/8 4/8 7/8 7/8 7/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 0/8 5/8 5/8 0/8 0/8 0/8 4/8 6/8 8/8 0/8
§basic functionality MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§constructor requires new No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No No Yes No
§Promise.prototype isn't an instance No Yes Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§Promise.all MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§Promise.all, generic iterables No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Promise.race MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No Yes Yes Yes No
§Promise.race, generic iterables No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Promise[Symbol.species] No No Yes Yes No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol MDN (Mozilla Development Network) logo  0/12 4/12 9/12 2/12 0/12 8/12 2/12 0/12 0/12 0/12 0/12 0/12 0/12 10/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 10/12 11/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12 11/12 12/12 12/12 12/12 12/12 0/12 0/12 4/12 12/12 12/12 0/12 9/12 9/12 10/12 10/12 12/12 12/12 12/12 12/12 0/12 0/12 0/12 0/12 0/12 0/12 10/12 0/12 0/12 0/12 0/12 11/12 12/12 11/12
§basic functionality No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§typeof support No Yes Yes No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§symbol keys are hidden to pre-ES6 code No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§Object.defineProperty support No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§symbols inherit from Symbol.prototype No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§cannot coerce to string or number No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§can convert with String() No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§new Symbol() throws No Yes Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§Object(symbol) No No No No No No[7] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§JSON.stringify ignores symbol primitives No No Yes No No Yes[10] Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No Yes Yes
§JSON.stringify ignores symbol objects No No Yes No No Yes[10] Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§global symbol registry No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§well-known symbols[19] 0/26 1/26 14/26 1/26 0/26 15/26 0/26 0/26 0/26 0/26 0/26 0/26 0/26 3/26 9/26 10/26 14/26 1/26 7/26 8/26 9/26 9/26 16/26 21/26 22/26 26/26 26/26 26/26 26/26 26/26 0/26 0/26 4/26 5/26 9/26 14/26 26/26 26/26 26/26 26/26 25/26 25/26 26/26 26/26 26/26 0/26 0/26 0/26 0/26 0/26 3/26 26/26 26/26 26/26 26/26 0/26 0/26 23/26 25/26 22/26 0/26 2/26 2/26 3/26 3/26 14/26 26/26 26/26 25/26 0/26 0/26 0/26 0/26 0/26 0/26 3/26 0/26 0/26 0/26 0/26 3/26 26/26 1/26
§Symbol.hasInstance MDN (Mozilla Development Network) logo  No No Flag No No No[7] No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.isConcatSpreadable MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.iterator, existence MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§Symbol.iterator, arguments object No No No No No No No No No No No No No Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Symbol.species, existence MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Array.prototype.concat No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Array.prototype.filter No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Array.prototype.map No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Array.prototype.slice No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Array.prototype.splice No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, RegExp.prototype[Symbol.split] No No No No No No No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.species, Promise.prototype.then No No Yes No No Yes[10] No No No No No No No No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.replace MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.search MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.split MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.match MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.match, RegExp constructor No No Yes No No Yes[10] No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.match, String.prototype.startsWith No No Yes No No Yes[10] No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.match, String.prototype.endsWith No No Yes No No Yes[10] No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.match, String.prototype.includes No No Yes No No Yes[10] No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.toPrimitive MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.toStringTag MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No Yes Yes Yes Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.toStringTag affects existing built-ins No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No Yes Yes Yes Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Flag Yes Yes Yes No No No No No No No No No No No No No Yes No
§Symbol.toStringTag, new built-ins No No No No No Yes[10] No No No No No No No No No No Yes No No No No No No No No Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.toStringTag, misc. built-ins No No Yes No No Yes[10] No No No No No No No No No No Yes No No No No No No No No Yes Yes Yes Yes Yes No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Flag Flag Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Symbol.unscopables MDN (Mozilla Development Network) logo  No No No No No No[7] No No No No No No No Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No[20] Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
Built-in extensions
§Object static methods 0/4 3/4 3/4 2/4 0/4 3/4 2/4 1/4 0/4 0/4 0/4 0/4 1/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 0/4 3/4 3/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 1/4 1/4 1/4 1/4 2/4 3/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4
§Object.assign MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.is MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes
§Object.getOwnPropertySymbols MDN (Mozilla Development Network) logo  No Yes Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes Yes
§Object.setPrototypeOf MDN (Mozilla Development Network) logo  No No No[13] No[13] No No[13] No[13] No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes Yes
§function "name" property MDN (Mozilla Development Network) logo  0/17 0/17 8/17 0/17 0/17 3/17 0/17 3/17 0/17 0/17 0/17 0/17 0/17 8/17 14/17 16/17 16/17 6/17 6/17 10/17 10/17 11/17 11/17 12/17 12/17 12/17 12/17 17/17 17/17 17/17 2/17 2/17 6/17 7/17 11/17 11/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 3/17 3/17 3/17 3/17 6/17 17/17 17/17 17/17 17/17 3/17 3/17 5/17 17/17 14/17 0/17 2/17 2/17 6/17 6/17 11/17 17/17 17/17 17/17 3/17 2/17 2/17 2/17 2/17 2/17 2/17 0/17 3/17 3/17 3/17 6/17 17/17 7/17
§function statements No No Yes No No Yes[10] No Yes No No No No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§function expressions No No Yes No No Yes[10] No Yes No No No No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§new Function No No No No No No No Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No[0] Yes Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No Yes Yes Yes Yes Yes Yes
§bound functions No No No No No No No No No No No No No Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§variables (function) No No Yes No No No No No No No No No No Flag Flag Flag Flag No No No No No No No No No No Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§object methods (function) No No Yes No No No No No No No No No No Flag Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§accessor properties No No No No No No No No No No No No No Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§shorthand methods No No Yes No No No No No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§shorthand methods (no lexical binding) No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§symbol-keyed methods No No No No No No No No No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§class statements No No No[21] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§class expressions No No No[21] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§variables (class) No No No[21] No No No No No No No No No No Flag Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§object methods (class) No No No No No No No No No No No No No Flag Yes Yes Yes No No No No No No No No No No Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§class prototype methods No No Yes No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§class static methods No No Yes No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§isn't writable, is configurable No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§String static methods 0/2 2/2 2/2 1/2 0/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 1/2
§String.raw MDN (Mozilla Development Network) logo  No Yes Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§String.fromCodePoint MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§String.prototype methods 0/10 8/10 9/10 7/10 0/10 9/10 7/10 0/10 0/10 0/10 0/10 0/10 0/10 9/10 10/10 10/10 10/10 8/10 9/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 0/10 0/10 0/10 9/10 10/10 10/10 10/10 10/10 0/10 0/10 9/10 10/10 10/10 0/10 1/10 1/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 0/10 0/10 0/10 1/10 2/10 0/10 0/10 0/10 0/10 9/10 10/10 2/10
§String.prototype.codePointAt MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§String.prototype.normalize MDN (Mozilla Development Network) logo  No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No No Yes No
§String.prototype.repeat MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§String.prototype.startsWith MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§String.prototype.startsWith throws on RegExp No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§String.prototype.endsWith MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§String.prototype.endsWith throws on RegExp No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§String.prototype.includes MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No[22] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag[22] Flag[22] Yes Yes Yes Yes Yes Yes No No No No No[22] No[22] No[22] No No No No Yes Yes No
§String.prototype[Symbol.iterator] MDN (Mozilla Development Network) logo  No Yes Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§String iterator prototype chain No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§RegExp.prototype properties MDN (Mozilla Development Network) logo  0/6 0/6 6/6 0/6 0/6 6/6 1/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 1/6 1/6 1/6 1/6 1/6 1/6 1/6 1/6 1/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 1/6 5/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 1/6 6/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 5/6 0/6 0/6 0/6 0/6 0/6 5/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 1/6 6/6 1/6
§RegExp.prototype.flags MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No No No Flag Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§RegExp.prototype[Symbol.match] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.replace] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.split] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.search] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array static methods 0/11 10/11 11/11 5/11 0/11 9/11 7/11 0/11 0/11 0/11 0/11 0/11 0/11 7/11 10/11 10/11 11/11 10/11 10/11 10/11 10/11 10/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 9/11 9/11 9/11 9/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 8/11 11/11 11/11 11/11 11/11 0/11 0/11 6/11 11/11 8/11 0/11 0/11 0/11 9/11 9/11 9/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 8/11 11/11 0/11
§Array.from, array-like objects MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from, generator instances No Yes Yes Yes No No[7] Yes No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.from, generic iterables No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from, instances of generic iterables No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from map function, array-like objects No Yes Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from map function, generator instances No Yes Yes No No No[7] Yes No No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.from map function, generic iterables No Yes Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from map function, instances of iterables No Yes Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.from, iterator closing No Yes Yes No No Yes[10] No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.of MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array[Symbol.species] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype methods 0/10 7/10 10/10 8/10 0/10 10/10 7/10 0/10 0/10 0/10 0/10 0/10 0/10 9/10 10/10 10/10 10/10 7/10 7/10 8/10 8/10 8/10 10/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 0/10 0/10 8/10 8/10 8/10 8/10 10/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 0/10 0/10 0/10 0/10 5/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 9/10 10/10 10/10 0/10 5/10 5/10 8/10 8/10 8/10 10/10 9/10 9/10 0/10 0/10 0/10 0/10 0/10 0/10 4/10 0/10 0/10 0/10 5/10 10/10 10/10 0/10
§Array.prototype.copyWithin MDN (Mozilla Development Network) logo  No No Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.prototype.find MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§Array.prototype.findIndex MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§Array.prototype.fill MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Flag Flag Yes Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§Array.prototype.keys MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Array.prototype.values MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes No[23] No[23] No[23] No[23] No[23] Yes No[24] No[24] No[24] No[24] No[24] No[24] No[24] No No No[23] No[23] No[23] No[23] Yes No No No No No No No No No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes No No No[23] Yes No No No No No No No No No[23] No No No No Yes Yes No
§Array.prototype.entries MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Array.prototype[Symbol.iterator] MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Array iterator prototype chain No No Yes No No Yes[10] No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No No Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.prototype[Symbol.unscopables] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Number properties 0/7 7/7 7/7 7/7 0/7 7/7 7/7 6/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 7/7 7/7 7/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 2/7 2/7 2/7 2/7 7/7 7/7 0/7 0/7 0/7 0/7 7/7 7/7 0/7
§Number.isFinite MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes No No No No Yes Yes No
§Number.isInteger MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Number.isSafeInteger MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Number.isNaN MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes No No No No Yes Yes No
§Number.EPSILON MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Number.MIN_SAFE_INTEGER MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Number.MAX_SAFE_INTEGER MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes No No No No Yes Yes No
§Math methods 0/17 17/17 17/17 15/17 0/17 17/17 17/17 14/17 0/17 0/17 0/17 0/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 0/17 1/17 15/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 17/17 17/17 17/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 0/17 0/17 1/17 1/17 17/17 0/17 0/17 1/17 15/17 17/17 17/17 5/17
§Math.clz32 MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Math.imul MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes No
§Math.sign MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No Yes Yes No
§Math.log10 MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes Yes
§Math.log2 MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes Yes
§Math.log1p MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.expm1 MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.cosh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.sinh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.tanh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.acosh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.asinh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.atanh MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.trunc MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes Yes
§Math.fround MDN (Mozilla Development Network) logo  No Yes Yes No No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes No
§Math.cbrt MDN (Mozilla Development Network) logo  No Yes Yes Yes No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes Yes
§Math.hypot MDN (Mozilla Development Network) logo  No Yes Yes No No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No Yes Yes Yes Yes
§Date.prototype[Symbol.toPrimitive] MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
Subclassing
§Array is subclassable 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 0/11 0/11 6/11 6/11 6/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 6/11 6/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 3/11 11/11 11/11 11/11 11/11 0/11 0/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 6/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 3/11 11/11 0/11
§length property (accessing) No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§length property (setting) No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§correct prototype chain No No No[13] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.isArray support No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Array.prototype.concat No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.filter No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.map No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.slice No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.splice No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.from No No[13] No[13] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.of No No[13] No[13] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp is subclassable 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 3/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 3/4 4/4 0/4
§basic functionality No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§correct prototype chain No No No[13] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype.exec No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§RegExp.prototype.test No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Function is subclassable 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 0/6
§can be called No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§correct prototype chain No No No[13] No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§can be used with "new" No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Function.prototype.call No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Function.prototype.apply No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Function.prototype.bind No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Promise is subclassable 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 2/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 0/4
§basic functionality No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§correct prototype chain No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Promise.all No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Promise.race No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§miscellaneous subclassables 0/6 0/6 0/6 2/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 0/6
§Boolean is subclassable No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Number is subclassable No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§String is subclassable No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Error is subclassable No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Map is subclassable No No No Yes No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Set is subclassable No No No Yes No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No Strict Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
Misc
§prototype of bound functions 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 3/5 3/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 0/5 0/5 4/5 5/5 3/5 0/5 0/5 0/5 0/5 3/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 5/5 1/5
§basic functions No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§generator functions No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§arrow functions No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§classes No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes Yes No No No No Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§subclasses No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Strict Strict Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No No Strict Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Proxy, internal 'get' calls MDN (Mozilla Development Network) logo  0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 14/36 19/36 20/36 20/36 17/36 20/36 22/36 24/36 24/36 27/36 35/36 36/36 36/36 36/36 36/36 36/36 36/36 0/36 0/36 0/36 0/36 21/36 25/36 36/36 36/36 36/36 36/36 36/36 35/36 35/36 35/36 35/36 0/36 0/36 0/36 0/36 0/36 0/36 36/36 36/36 36/36 36/36 0/36 0/36 19/36 35/36 0/36 0/36 0/36 0/36 0/36 0/36 25/36 36/36 36/36 36/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 0/36 36/36 7/36
§ToPrimitive No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§CreateListFromArrayLike No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§instanceof operator No No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§HasBinding No No No No No No No No No No No No No No No Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No[20] Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§CreateDynamicFunction No No No No No No No No No No No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§ClassDefinitionEvaluation No No No No No No No No No No No No No Flag Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§IteratorComplete, IteratorValue No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§ToPropertyDescriptor No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Object.assign No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Object.defineProperties No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Function.prototype.bind No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Error.prototype.toString No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§String.raw No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp constructor No No No No No No No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype.flags No No No No No No No No No No No No No No No Flag Flag Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype.test No No No No No No No No No No No No No No No Flag Flag No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype.toString No No No No No No No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No ? No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§RegExp.prototype[Symbol.match] No No No No No No No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.replace] No No No No No No No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.search] No No No No No No No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§RegExp.prototype[Symbol.split] No No No No No No No No No No No No No No No Flag Flag No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.from No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.concat No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype iteration methods No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.pop No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.reverse No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.shift No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.splice No No No No No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Flag Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.toString No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§JSON.stringify No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Promise resolve functions No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§String.prototype.match No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§String.prototype.replace No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§String.prototype.search No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No No Yes Yes Yes No No No No No No No No No No No No Yes No
§String.prototype.split No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Date.prototype.toJSON No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Proxy, internal 'set' calls MDN (Mozilla Development Network) logo  0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 11/11 5/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 11/11 0/11 0/11 3/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 11/11 11/11 11/11 11/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 0/11 11/11 7/11
§Object.assign No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.from No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.of No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.copyWithin No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.fill No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.pop No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.push No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.reverse No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.shift No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.splice No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.unshift No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Proxy, internal 'defineProperty' calls MDN (Mozilla Development Network) logo  0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 0/2
§[[Set]] No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§SetIntegrityLevel No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Proxy, internal 'deleteProperty' calls MDN (Mozilla Development Network) logo  0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 1/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 5/6
§Array.prototype.copyWithin No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Array.prototype.pop No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.reverse No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.shift No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.splice No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Array.prototype.unshift No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Proxy, internal 'getOwnPropertyDescriptor' calls MDN (Mozilla Development Network) logo  0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 2/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 0/4
§[[Set]] No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Object.assign No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Object.prototype.hasOwnProperty No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Function.prototype.bind No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Proxy, internal 'ownKeys' calls MDN (Mozilla Development Network) logo  0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 0/3 0/3 0/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 3/3 1/3
§SetIntegrityLevel No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§TestIntegrityLevel No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§SerializeJSONObject No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Object static methods accept primitives 0/10 0/10 10/10 0/10 0/10 10/10 10/10 0/10 0/10 0/10 0/10 0/10 0/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 0/10 0/10 0/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 9/10 10/10 10/10 0/10 0/10 0/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 10/10 10/10 10/10
§Object.getPrototypeOf MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.getOwnPropertyDescriptor MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.getOwnPropertyNames MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.seal MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.freeze MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.preventExtensions MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.isSealed MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.isFrozen MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.isExtensible MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§Object.keys MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§own property order 0/7 0/7 1/7 0/7 0/7 1/7 1/7 0/7 0/7 0/7 0/7 4/7 4/7 7/7 7/7 7/7 7/7 2/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 4/7 4/7 3/7 3/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 2/7 2/7 3/7 4/7 5/7 7/7 7/7 7/7 7/7 0/7 2/7 3/7 7/7 5/7 0/7 3/7 3/7 3/7 3/7 7/7 7/7 7/7 7/7 3/7 3/7 3/7 3/7 3/7 3/7 3/7 0/7 2/7 3/7 4/7 5/7 7/7 6/7
§Object.keys No No No No No No No ? No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Object.getOwnPropertyNames No No No No No No No No No No No Yes[0] Yes[0] Yes[0] Yes[0] Yes[0] Yes[0] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes Yes
§Object.assign No No No No No No No No No No No No No Yes[0] Yes[0] Yes[0] Yes[0] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§JSON.stringify No No No No No No No No No No No Yes[0] Yes[0] Yes[0] Yes[0] Yes[0] Yes[0] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes
§JSON.parse No No No No No No No No No No No Yes[25] Yes[25] Yes[25] Yes[25] Yes[25] Yes[25] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§Reflect.ownKeys, string key order No No No[26] No[26] No No[26] No[26] No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Reflect.ownKeys, symbol key order No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§miscellaneous 1/10 1/10 6/10 3/10 1/10 6/10 2/10 1/10 0/10 0/10 0/10 3/10 3/10 7/10 7/10 7/10 8/10 5/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 9/10 10/10 10/10 10/10 3/10 3/10 6/10 6/10 8/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 2/10 2/10 2/10 2/10 5/10 10/10 10/10 10/10 10/10 2/10 2/10 5/10 8/10 9/10 0/10 2/10 2/10 6/10 6/10 10/10 10/10 10/10 10/10 2/10 2/10 2/10 2/10 2/10 2/10 2/10 0/10 2/10 2/10 2/10 5/10 10/10 7/10
§no escaped reserved words as identifiers Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§duplicate property names in strict mode No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes Yes
§no semicolon needed after do-while No No Yes Yes No Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§no assignments allowed in for-in head in strict mode No No Yes Yes No Yes No No No No No No No No No No Yes No No No No No No No No No Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§accessors aren't constructors No No No No No No No No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§Invalid Date No No Yes No No Yes[10] Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§RegExp constructor can alter flags No No Yes No No Yes[10] Yes No No No No No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No Yes Yes No No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§RegExp.prototype.toString generic and uses "flags" property No No Yes No No Yes[10] No No No No No No No No No Flag Flag No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No ? ? Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
§built-in prototypes are not instances No No No No No No No No No No No No No No No Flag Flag No No No No No No No No No No Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No No Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§function 'length' is configurable No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes
Annex b
§non-strict function semantics[27] 0/3 0/3 0/3 0/3 0/3 0/3 0/3 2/3 0/3 0/3 0/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 2/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 2/3 2/3 2/3 2/3 2/3 3/3 3/3 3/3 3/3 3/3 2/3 0/3 2/3 3/3 0/3 2/3 2/3 2/3 2/3 3/3 3/3 3/3 3/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 0/3 2/3 2/3 2/3 2/3 3/3 2/3
§hoisted block-level function declaration No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes No No No Yes No No No No No Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§labeled function statements No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§function statements in if-statement clauses No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§__proto__ in object literals MDN (Mozilla Development Network) logo [28] 0/5 0/5 0/5 0/5 0/5 0/5 0/5 1/5 0/5 0/5 0/5 0/5 1/5 3/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 1/5 1/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 1/5 1/5 1/5 2/5 5/5 5/5 5/5 5/5 5/5 1/5 1/5 0/5 5/5 5/5 0/5 1/5 1/5 5/5 5/5 5/5 5/5 5/5 5/5 1/5 1/5 1/5 1/5 1/5 1/5 1/5 0/5 1/5 1/5 2/5 5/5 5/5 0/5
§basic support No No No No No No No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§multiple __proto__ is an error No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§not a computed property No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No Yes Yes Yes No
§not a shorthand property No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§not a shorthand method No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes No No No Yes Yes No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§Object.prototype.__proto__ MDN (Mozilla Development Network) logo  0/6 0/6 0/6 0/6 0/6 0/6 0/6 3/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 5/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 3/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 4/6 6/6 2/6 6/6 6/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 3/6 2/6 2/6 2/6 6/6 6/6 6/6 0/6 3/6 6/6 6/6 6/6 6/6 6/6
§get prototype No No No No No No No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§set prototype No No No No No No No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§absent from Object.create(null) No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes
§present in hasOwnProperty() No No No No No No No Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§correct property descriptor No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes
§present in Object.getOwnPropertyNames() No No No No No No No No No No No No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes No No Yes Yes Yes Yes Yes
§String.prototype HTML methods 0/3 0/3 3/3 0/3 0/3 3/3 3/3 3/3 0/3 0/3 0/3 1/3 1/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 2/3 3/3 3/3 3/3 3/3 0/3
§existence MDN (Mozilla Development Network) logo  No No Yes No No Yes[10] Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§tags' names are lowercase No No Yes No No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§quotes in arguments are escaped No No Yes No No Yes[10] Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes No
§RegExp.prototype.compile MDN (Mozilla Development Network) logo  0/2 0/2 0/2 0/2 0/2 0/2 0/2 1/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 2/2 2/2 2/2 0/2 1/2 1/2 1/2 1/2 1/2 2/2 2/2 2/2 2/2 1/2 1/2 0/2 1/2 0/2 0/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 0/2 1/2 1/2 1/2 1/2 2/2 0/2
§basic functionality No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§returns this No No No No No No No ? No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes Yes Yes No No No No No No Yes Yes Yes Yes ? No No ? No No No No No No No No No No No No No No No No No No No No No No Yes No
§RegExp syntax extensions 0/8 0/8 0/8 0/8 0/8 0/8 0/8 8/8 0/8 0/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 6/8 6/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 4/8 5/8 8/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 8/8 8/8 8/8 8/8 8/8 3/8
§hyphens in character sets No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§invalid character escapes No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§invalid control-character escapes No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§invalid Unicode escapes No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§invalid hexadecimal escapes No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§incomplete patterns and quantifiers No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes
§octal escape sequences No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§invalid backreferences become octal escapes No No No No No No No Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
§HTML-style comments No No No No No No No Yes No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No
__createIterableObject(), used in the numerous "generic iterables" tests, is defined as:

[1] Flagged features have to be enabled via "Experimental Javascript features" flag unless otherwise stated

[2] Flagged features require an optional transformer setting.

[3] Results are only applicable for the KHTML rendering engine.

[4] Flagged features have to be enabled via "Enable experimental Javascript features" setting under about:flags

[5] Flagged features have to be enabled via --harmony or --es_staging flag

[6] Requires the properTailCalls compile option.

[7] TypeScript's compiler will accept code using this feature if the --target ES6 flag is set, but passes it through unmodified and does not supply a runtime polyfill.

[8] This compiler requires generic iterables have either a Symbol.iterator or non-standard "@@iterator" method.

[9] Firefox incorrectly produces an error in strict mode if the method is named "arguments", "eval", or "delete".

[10] This feature is supported when using TypeScript with core-js, or when a native ES6 host is used.

[11] Available for code in a <script type="application/javascript;version=1.7"> (or version=1.8) tag.

[12] Note that prior to ES6, it was recommended that ES5 implementations forbid block-level declarations in strict mode.

[13] Requires native support for Object.prototype.__proto__

[14] This compiler transforms extends into code that copies properties from the superclass, instead of using the prototype chain.

[15] TypeScript transforms extends into code that copies static properties from the superclass (but uses the prototype chain for instance properties).

[16] This feature requires native generators or regenerator-runtime, it's a part of babel-polyfill or babel-runtime.

[17] The 2015 version of the specification also specifies an "enumerate" handler, which was removed in the 2016 version.

[18] The 2015 version of the specification also specifies Reflect.enumerate, which was removed in the 2016 version.

[19] Functionality for Symbol.iterator is tested by the "generic iterators" subtests for the spread (...) operator, for..of loops, destructuring, yield *, and Array.from.

[20] with is not supported in ejs

[21] Requires function "name" properties to be natively configurable

[22] Available as the draft standard String.prototype.contains

[23] Available as Array.prototype[Symbol.iterator]

[24] The feature is enabled by default only in Firefox Nightly due to compatibility issue.

[25] Unlike other engines, Chakra sorts properties removed by delete, then recreated by assignment, to their original creation positions, not their latest positions.

[26] This uses native for-in enumeration order, rather than the correct order.

[27] The 2015 version of the specification contains multiple bugs for hoisted block-level function declaration semantics, which these tests disregard.

[28] Note that this is distinct from the existence or functionality of Object.prototype.__proto__.